Sulphur dye preparations



Patented Sept. 29, 1936 UNITED STATES PATENT OFFICE SULPHUR DYEPREPARATIONS No Drawing.

Application December 22, 1933,

Serial No. 703,667. In Germany December 24,

5 Claims.

Various proposals have been made in respect of the manufacture ofsulphur dyes soluble in water; for instance, by evaporating the acid dye(disulphide) with sodium sulphide (Lange, Schwefelfarbstoffe, Aufiage1925, page 179) The dye has also been brought in a similar manner into afluid or pasty form (Anmeldung F. 19 945; Friedlander VIII, 824; seealso Leipziger Monatshefte fiir Textilindustrie 1905, page 267, LehnesFarberzeitung 1905, page 234;; Anmeldung A. 14 985; Friedlander IX,478). Such fluid commercial dyes, however, can be obtained only in a lowdegree of concentration in comparison with the dry dye since otherwisesegregation and crystallization occur. A further disadvantage of thesedyes, soluble in water, is that in making the dye-bath it is necessaryto add a certain quantity of alkali metal sulphide, a condition which isunfavorable, particularly in connection with export trade. Attempts havetherefore been made to produce sulphur dyes which yield practicabledye-baths without further addition of alkali metal sulphide. Usefulresults have been obtained only in the case of black sulphur dyes, suchas are obtained from dinitrophenol or mixtures of dinitroandtrinitrophenol. No useful dye preparations containing the quantity ofsodium sulphide requisite for the dye bath have hitherto been obtainablein the case of colored sulphur dyes because during the concentration anddrying of the dye containing such a quantity of sodium sulphide,products of decomposition and degradation are produced.

According to the present invention, useful dye preparations of highconcentration and soluble in water are obtained from all sulphur dyes byconverting them into the reduced form by means of a quantity of reducingagent sufiicient to provide after reduction the quantity of sodiumsulphide requisite for the dye-bath, under such conditions thatdegradation or decomposition by the setting up of hydrolysis (freealkali) is avoided during the operation. As is known, only the reducedor leuco-form of sulphur dyes has afiinity for the fiber, so thepreparations made in accordance with this invention are already in aform suitable for use. They have the advantage that they are soluble inwater at the ordinary temperature and have an affinity for the fiber inthe dye-bath at room temperature without further addition of alkalimetal sulphide. Corre spondingly with the properties of the individualdyes the best dyeing may be obtainable at the ordinary temperature or ata raised temperature.

For the dye-house, these dye preparations constitute a considerableprogress.

The conversion of the sulphur dyes into a concentrated reduced formcontaining sodium sulphide can be attained by avoiding hydrolysis if oneof the following conditions is observed:-

(1) The use of reducing agents by which the hydrolysis is suppressed,for example NaSI-I or a mixture of NazS and NaSH.

(2) The use of a temperature for the reduction which is below theboiling point of the reducing bath.

(3) The use of a reducing bath of such concentration that its content ofalkali metal sulfide is not less than about 30 per cent. (calculated ona molecular weight of 78).

In particular cases, such as in the case of sulphurized baked dyes(obtained by melting a mixture of an aromatic base with sulphur), it ispossible to conduct the leaching of the sulphur melt, that is to say,the conversion into the form soluble in alkali metal sulphide, withcaustic soda; without isolation of the sulphur dye obtained it ischanged into the reduced form containing sodium sulphide by a furtheraddition of NazS, or NaSI-I.

From the dye bath made with the dye preparations and of the usualconcentration, dyeings are obtained which have properties of fastnessequal to those which can be obtained by known methods.

The following examples illustrate the invention:

Example 1.The dye obtained by treating with an alkali metal polysulphidethe leucoindophenol- 3-methyl-4-amino-4-oxydiphenylamine is precipitatedin the usual manner and pressed; 100 kilos of the dye are introduced, at50 (3., in the form of a press-cake, into- 3'70 kilos of sodiumhydrosulphide solution of per cent. strength. When the reduction isfinished the whole is heated to C. and the dye paste dried on rollers orin a vacuum at to C. The highly concentrated dye preparation thusobtained dissolves completely in water, even at the ordinarytemperature, and dyes the fiber, even at room temperature, withoutfurther addition of alkali sulphide. The dyeing produced is a vivid blueof good fastness to light and washing.

Example 2.The dye press-cake obtained from the condensation product fromdiphenylamine- Z-carboxylic acid and nitrosophenol by treatment with analkali metal polysulphide, is dried. 100 kilos of the dried dye areintroduced, at ordinary temperature, into 340 kilos of sodiumhydrosulphide solution of 30 per cent. strength. When the reduction iscomplete, the mass is stirred for an hour at 50 C. and the dye pastedried as described in Example 1. The dyeing obtained with thispreparation has the properties described in Example 1.

Example 3.The dye obtained from trinitrophenol by boiling under refluxwith an aqueous solution of sodium polysulphide is precipitated by meansof air and separated by filtration. The filter-cake, corresponding with100 kilos of dry dye, and containing about 25 per cent. of water, isstirred at 50 C. with 180 kilos of sodium hydrosulphide of 40 per cent.strength, and 40 kilos of calcined sodium sulphide are then introduced,whereupon the mass is heated to C. The working up and properties of thedye are as described in Example 1. The dye dyes cotton violetblacktints, which are somewhat developed in the boiling bath.

Example 4.-The yellow sulphur dye obtained from 50 kilos ofmeta-toluylenediamine by introducing into 100 kilos of sulphur andfinally heating to about 190 C. is isolated in known manner. The drieddye is then stirred with crystallized sodium sulphide at C. and workedup as described in Example 1. kilos of dye need about 400 kilos ofcrystallized sodium sulphide.

The dye preparation obtained dissolves freely in water and dyes cottonin the dye-bath thus prepared yellow tints of good fastness.

Example 5.100 kilos of the crude mass obtained by heating slowly partsof meta-toluylenediamine and 100 parts of para-phenylenediamine, with500 parts of sulphur to 200 C. and then raising the temperature in 4hours to 240 C. are treated with 200 kilos of caustic soda lye of 35 B.and, after addition of 157 kilos of crystallized sodium sulphide, thewhole is dried on rollers under vacuum or in a vacuum chest. The dyeobtained has the properties described in Example 4. It dyes cotton olivetints.

What I claim is:

1. The process for manufacturing sulphur dye preparations containing thequantity of alkali metal sulphide requisite for the dye-bath, whichcomprises adding to the aqueous solution of the sulphur dye the requiredamount of alkali metal sulphide and evaporating the water withouthydrolysis of the alkali metal sulphide.

2. The process for manufacturing water-soluble sulphur dye preparationscontaining the quantity of alkali metal sulphide requisite for thedye-bath, which comprises treating the sulphur dye in the presence ofwater with a reducing agent of the general formula XSalkali metalwherein X is hydrogen or an alkali metal, and evaporating the water fromthe preparation in the presence of the alkali metal sulphide requiredfor preparing the dye-bath, without hydrolysis of the said reducingagent.

3. The process for manufacturing water-soluble sulphur dye preparationscontaining the quantity of alkali metal sulphide requisite for thedye-bath, which comprises treating the sulphur dye in the presence ofwater with a reducing agent of the general formula XSalkali metalwherein X is hydrogen or an alkali metal, and evaporating the water fromthe preparation in the presence of the alkali metal sulphide requiredfor preparing the dye-bath, at a temperature below the normal boilingpoint of the reducing bath.

4. The process for manufacturing water-soluble sulphur dye preparationscontaining the quantity of alkali metal sulphide requisite for thedye-bath, which comprises treating the sulphur dye in the presence ofwater with a reducing agent of the general formula XSalkali metalwherein X is hydrogen or an alkali metal and evaporating the water fromthe dye solution in the presence of the alkali metal sulphide requiredfor preparing the dye-bath, the said dye solution having a content ofalkali metal sulphide of at least 30 per cent. calculated on anhydroussulphide.

5. The process for manufacturing water-soluble sulphur dye preparationscontaining the quantity of alkali metal sulphide requisite for thedye-bath, which comprises treating the sulphur dye in the presence ofwater with an alkali metal hydrosulphide and evaporating the water fromthe dye solution in the presence of the alkali metal hydrosulphiderequired for preparing the dye-bath.

WALTER HAGGE.

